F-1 Engine Injector

Although I've seen
injectors before, and even viewed the recovered injectors, when one is
used to seeing
photos that were taken from at least 10 or 18 feet away from the injector
(depending on whether there was a nozzle extension mounted on the engine), one
can't be help but be amazed at just how physically massive the injector
actually is.

The injector was displayed with a fence around it, with the injector
sufficiently far removed so as to prevent the public from reaching over and
touching it. There were four objects, placed 90 degrees apart, on the floor
around the injector. I asked the security guard if she knew what they were,
and she sort of rolled her eyes and said that they were motion detectors. "I
mean, the injector weighs 1,200 pounds. How is anyone going to steal that?!"